naming: localise liturgical day names in any language

Add internal/naming, which renders temporal day names and celebration
display names from the calendar engine's slugs in any language. English is
the built-in baseline; a language is data -- an embedded lang/<code>.ini
(pl shipped) and/or a user file at <config dir>/names/<code>.ini that
overrides it key by key. Names compose from a small vocabulary plus
per-language format templates, so word order and grammatical case can
differ (e.g. Polish genitive "3. Niedziela Okresu Zwykłego"); any string a
language omits falls back to English.

- Move day-name generation out of calendar (calendar.HumanizeSlug removed,
  calendar stays a pure engine) into naming.DayName; the English golden
  cases carry over verbatim.
- naming.CelebrationName unifies the three duplicated resolvers
  (cli/readings/calfeed): name.<lang> -> English -> Latin -> humanized slug.
  Saint names stay in the calendar data (name.<lang>), overridable via
  calendar layers.
- config: ui_language now accepts any code (lower-cased, not clamped to
  en/pl) so names/<code>.ini applies; UI chrome still resolves en/pl and
  falls back to English. Add NamesDir(); wire naming.SetUserDir (and the
  previously unwired bible.SetUserCorporaDir) in the TUI and web mains too,
  so external corpora and name files work across all three binaries.

2 files changed, 10 insertions, 14 deletions

diff --git a/internal/cli/cli.go b/internal/cli/cli.go
index c4f063d..1fc7ac0 100644
--- a/internal/cli/cli.go
+++ b/internal/cli/cli.go
@@ -19,6 +19,7 @@ import (
 	"github.com/lukaszkasprzak/lectio/internal/export"
 	"github.com/lukaszkasprzak/lectio/internal/i18n"
 	"github.com/lukaszkasprzak/lectio/internal/liturgy"
+	"github.com/lukaszkasprzak/lectio/internal/naming"
 	"github.com/lukaszkasprzak/lectio/internal/readings"
 	"github.com/lukaszkasprzak/lectio/internal/render"
 )
@@ -203,6 +204,9 @@ func Run(args []string, stdin io.Reader, stdout, stderr io.Writer) int {
 	if dir, err := config.CorporaDir(); err == nil {
 		bible.SetUserCorporaDir(dir)
 	}
+	if dir, err := config.NamesDir(); err == nil {
+		naming.SetUserDir(dir)
+	}
 	if lectionary != "" {
 		cfg.Lectionary = lectionary
 	}
diff --git a/internal/cli/liturgy.go b/internal/cli/liturgy.go
index 07a87bc..9d7f3b6 100644
--- a/internal/cli/liturgy.go
+++ b/internal/cli/liturgy.go
@@ -11,6 +11,7 @@ import (
 	"github.com/lukaszkasprzak/lectio/internal/calendar"
 	"github.com/lukaszkasprzak/lectio/internal/config"
 	"github.com/lukaszkasprzak/lectio/internal/i18n"
+	"github.com/lukaszkasprzak/lectio/internal/naming"
 	"github.com/lukaszkasprzak/lectio/internal/render"
 )
 
@@ -149,23 +150,14 @@ func printLiturgicalDay(out io.Writer, cfg config.Config, tbl *bible.BookTable,
 	}
 }
 
-// celebrationName is the celebration's name in the UI language (falling back to
-// English, then a humanized slug for temporal days that carry no proper name).
+// celebrationName is the celebration's name in the UI language, resolved by
+// naming.CelebrationName (name.<lang> -> English -> Latin -> humanized slug).
+// A bare, unnamed feria renders as "(feria)".
 func celebrationName(cfg config.Config, c calendar.Celebration) string {
-	lang := "en"
-	if cfg.UILanguage == "pl" {
-		lang = "pl"
-	}
-	if n := c.Name[lang]; n != "" {
-		return n
-	}
-	if n := c.Name["en"]; n != "" {
+	if n := naming.CelebrationName(cfg.UILanguage, c); n != "" {
 		return n
 	}
-	if c.Slug == "" {
-		return "(feria)"
-	}
-	return calendar.HumanizeSlug(c.Slug)
+	return "(feria)"
 }
 
 func rankLabel(r calendar.Rank) string {